Well I wouldn’t say it is rubbish - looks like 'Garden Treasure' to me. Alas it isn't a tooth but mineral matrix of some ilk. Our mineralogist has eyeballed it and feels that the white portion looks quite calcite like. It's an intriguing object I would keep this in my box of 'Garden Treasure' if I had found it.

It looks like a pig canine (tusk) to me. In the first photo (the one with a pond coin) I can see the base of the root, with the hole in it. The brown half is the root, the white one the crown covered in enamel. You could bring the specimen to the Museum so we can examine it.